The invention relates to a tool magazine system for a machining spindle, comprising a gripper which picks up tools from a tool magazine, guides them to a machining spindle, for example of a machining center or machine tool, and passes them to said spindle.
Tool magazine systems of this type are well known. In machine tools such as machining centers, cutting machines or lathes, particularly for the metal-processing industry, their function is to make a wide variety of tools available in rapid sequence according to the predetermined machining steps of the tool spindle. The tools in question are generally cutting tools such as drills or milling cutters. But it is perfectly possible to provide a machining head instead of a machining spindle, the head possibly having a tool spindle.
The known solution has the disadvantage that the arrangement of the tool magazine, in which several hundred very different tools are stored, takes up a very large space. Known systems pick up the tools from above, which necessitates a flat arrangement of the tools adjacent one another. At the same time the manipulator which handles the gripper needs a corresponding amount of space, resulting in very large installations.
The object of the present invention is therefore to provide an improved tool magazine system of the type described above, so as to enable a larger number of tools to be accommodated in the tool magazine system, while maintaining the same area requirement.
The present invention provides a tool magazine system for a machining spindle, comprising a gripper which picks up tools from a tool magazine, guides them to a machining spindle and passes them to a spindle wherein said gripper is fed to said tool laterally with respect to the axis of rotation, or longitudinal axis, of said tool, particularly substantially at right angles to that axis, and should grasp said tool.
This construction according to the invention allows tools to be superimposed along the longitudinal axis, vertically in the case of a rack, yet allows said tools to be grasped and transported securely. As it is in principle possible to store a plurality of tools above each other there is no problem in having said tool magazine in the form of a rack, and hence the area requirement can be considerably reduced.
The invention is in no way restricted to having said tools superimposed along the longitudinal axis, e.g. vertically. Similarly it may also be applied to existing tool magazines where said tools are e.g. juxtaposed flat or offset in a stepped arrangement. Said tool magazine system according to the invention can also accommodate tools stored in a lying position, i.e. tools with their longitudinal axis substantially horizontal.
In the tool magazine system according to the invention, the gripper approaches the tool laterally with respect to the longitudinal/rotational axis of said tool. In the state of the art, movement substantially along the longitudinal or rotational axis was envisaged (usually vertically from above), as the gripper means grasped said tool or tool shank in an axial direction. To permit these various complex movements of the gripper, said gripper is arranged on a manipulator and mounted for multi-axial movement. There may for example be a five or six-axis system with three translatory axes and two, three or even more rotational axes being provided for the gripper.
In a preferred embodiment of the tool magazine system according to the invention, a drip trough for collecting dispersed cooling liquid is provided below the tool magazine, and said drip trough is connected to the cooling liquid circuit. When the operation is started, the tool is sprayed with cooling liquid, firstly to lower its temperature and secondly to float away the detached chips. Said cooling liquid is in a circuit and, when the floated-off particles have been cleaned or filtered off, the liquid is fed by a pumping system to the tool or workpiece and sprayed onto the tool or workpiece at high pressure. When the particular step in the operation is terminated the dripping wet tool is removed from the work spindle or machining head by the gripper and transported back into the magazine. The cooling liquid clinging to it is also dispersed into the tool magazine. While the tool is out of action the liquid drips off it and is caught in the drip trough proposed according to the invention, which returns the collected liquid to the cooling liquid circuit.
To prevent all the other tools below the dripping one from being fouled with the cooling liquid mixed with abraded chips and the like, a drip sheet is provided in the storage means for the tools, so that the tool below it is protected from the liquid as by a rain canopy.
The invention further provides a gripper for taking hold of, conveying and/or passing on a tool, particularly for conveying a tool from a tool magazine to a work spindle, the tool in particular having a shank, wherein a groove, recess or shoulder with which a first member of the gripper interacts is provided in the surface of the shank or tool, and a second member of the gripper interacts with a different region of the shank or tool.
As with the form of the tool magazine system according to the invention, an improved gripper is similarly proposed, allowing the tool to be grasped substantially at right angles or laterally with respect to its preferred axis. Two different, competitive systems are substantially known for grasping tools. One is a so-called flap system, where two elements are moved axially or at an acute angle to that axis and the flaps are constructed so that they engage in the shoulders and shanks or, respectively, in slots or grooves in the tool and are held therein. Another principle operates like tongs, that is to say, the tool is picked up in an axial direction. In the state of the art solution however special undercut portions, shoulders and the like on the tool or tool shank are regularly used to hold the tool. It is often also desirable for the tool to be passed from one gripper to another, e.g. for a first gripper to take it out of the magazine and a second gripper to be responsible for inserting the tool in the work head/spindle. The known principles do not apply here, as they are generally only unilateral, i.e. they only allow the tool to be grasped at one side by the gripper.
The form of gripper now proposed according to the invention therefore also allows another gripper system, namely one approaching the tool laterally or at right angles according to the movement of the gripper. For this purpose it is proposed that the second member of the gripper should lie against the surface of the shank or the outside diameter of the tool. The second member is shaped so that it need not be held on shoulders, axial slots and the like, as was necessary in the prior art. Instead the second member is positioned on the surface of the shank or the outside diameter of the tool so that the tool is guided radially of the gripper and fixed. The axial guidance is provided by the first member, which interacts with a corresponding lug, a projection or a recess, groove or the like in the tool.
It has been indicated that a shank is provided on the tool, its external profile or outside diameter being considerably larger than the diameter of the tool. The invention is not however restricted to such a structure. It may be used in the same way in a tool without a shank, in which case the tool surface takes over the corresponding functions of the shank surface. The same applies to tools of the type where said shank is set back from the effective parts of the tool.
Use of the shank does however have a function, particularly in automatic machining of workpieces: it defines in terms of contact surfaces the exact position of the tool in a longitudinal direction and also relative to the diameter for correspondingly accurate machining. A plane face is provided on the shank for this purpose, particularly at right angles to the longitudinal axis; it is described as the functional surface and is machined extremely accurately. Known grasping principles have particularly included the functional surface for holding the tool. Such a principle is disadvantageous, firstly because the functional surface may be damaged as a result of the holding forces. Secondly chips and the like may be left on the plane face under the grasping member and may not be removed from the tool, even if a frequently envisaged subsequent blowing-off step is carried out when moving the tool into and out of the magazine. In spite of the planned cleaning step chips may therefore be left on the highly accurate contact surfaces, e.g. with a steep taper or an HSK shank. They may then be transported into the tool support on the work spindle, where they will cause measuring inaccuracies. But almost as a side effect, the solution according to the invention makes it unnecessary to include the functional surfaces for holding the tool; instead these surfaces are kept exposed and may be cleaned optimally with compressed air or a flushing liquid or the like.
A further advantage of the gripper structure is that it is comparatively compact, as said first member engages e.g. in the groove in the tool and said second member is juxtapoed, lying against the surface of the shank. If this principle is reflected in an axis or plane at right angles to the longitudinal axis, a gripper thus arranged can also grasp into the groove and another part of the shank. So with this principle, it is basically possible for two grippers to grasp the tool simultaneously. However this is the basic prerequisite for an encircling system comprising two grippers.
The gripper structure according to the invention provides three advantages: firstly it allows the tools to be arranged compactly in a tool rack; secondly it allows the workpiece to be encircled directly without using an additional encircling element and thirdly the gripper structure is chosen so that the functional surfaces are not required for holding, i.e. they cause no problems even when the tool is inserted in the work spindle, and the surfaces are accessible for cleaning.
In a preferred embodiment of the tool magazine system according to the invention, the first member and the second member can be moved relative to each other, and in particular can be moved linearly or swivelled towards each other. The proposed mobility allows the tool to be grasped and the relative mobility may be brought about by three different principles, namely solely by movement of the first or the second member or by movement of both members. According to the mount and the choice of drive it is advantageous for the first and second members either to be movable linearly towards each other or to be swivelled towards each other, e.g. if one member is hinged.
In a preferred embodiment of the tool magazine according to the invention, the first member is stationary relative to the gripper and the second member is constructed for movement towards it. The first member is preferably formed with a spring-like contact surface which engages in a peripheral groove in the shank. The second member, which is responsible for fixing the tool in a radial direction (the tool being fixed in an axial direction by the first member), is movable towards it.
Of course, it is similarly possible for the kinematics to be appropriately exchanged.
The invention also relates to a machine tool equipped with either a gripper, a tool magazine system or an encircling system as described. A machine tool of this type is employed particularly for machining workpieces, but it can also be used for other purposes, for example this principle may be applied to assembly machines where appropriate assembly tools are mounted in the work head by means of the invention.